Magic Monday Journal Club

March the 3d  2014

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Hey guys. Was nice to meet you all there...

The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Comelling Case for Annihilating Dark Matter

by T. Daylan, D. P. Finkbeiner, D. Hooper,  T.Linden,  S. K. N. Portillo, N. L. Rodd,  and T. R. Slatyer.

These bunch of authors, are used to give us around 2 to 4 new DM signals every year. 2014 will not be an exception for sure. They took back the FERMI data, remade a refined analysis to conclude that the famous bump at 1 GeV observed by the satellite can in fact be explained in the context of a dark matter of around 30-40 GeV annihilating mainly into quark final states (bbar and ccbar) with a cross section σv of around 2 x 10^-26  which would corresponds to a thermal candidate. They exclude the previous hypothesis of Hooper et all of a 8 GeV DM decaying into tau tau that was used a time to explain at the same time this bump in the FERMI spectrum and the WMAP/PLANCK synchrotron-like haze. What to think about it? After all these indirect signals since two years (from keV to 130 GeV passing through 1 GeV), I do not have any opinion. Just brain washed. For the hurry guys, you just have to look at their Fig.15. A loophole? I would say watching their Fig.17 makes ma thing a millisecond pulsar is not so far from a regular astrophysical explanation. But they claimed no. So I believe them (do I have the choice?). You will find an annotated version of the paper around this place.

Observation of photon polarization in the b -> sγ transition

by LHCb collaboration

In B-to-s-gamma decays in the SM the photon is predicted to have mostly left-handed polarization (because it recoils against a left-handed quark).  The LHCb analysis detects the photon polarization  in B+ -> K+ \pi+ \pi- \gamma  decays with the 5.2 sigma significance.  In the near future this observable may become an important handle to constrain (or discover) physics beyond the SM.

Search for Low-Mass WIMPs with SuperCDMS

by CDMS collaboration

SuperCDMS released his first result, concentrating on  the low mass region. As we expected,  the ~8 GeV dark matter favored

by DAMA et al. are excluded. Just  go to their Fig.4, all is there..

Benchmarks for Dark Matter Searches at the LHC

by A. De Simone, G.-F. Giudice and A. Strumia

A nice italian team who gives us a really clear paper which synthesizes the last constraints on benchmarks model with t-channel colored particle exchanged and s-channel Higgs- or Z-portal. Easy to read, good references, nice summary of the situation. Typical plots to include in the slides of your next talk are the Figures 3 and 4. All is there, explicit. Do not hesitate to take it to read tonight while your family sleeps. You can find an annotated version of the paper there.

An X-ray Line from eXciting Dark Matter

by D. P. Finkbeiner and N. Weiner

The exciting dark matter (XDM) is a model that can explain any astrophysical photon line measured in any part of the spectrum.  Logically, XDM was applied to explain the recently detected 3.5 keV x-ray line.

Lepton Portal Dark Matter

by Y. Bai and J. Berger

Mmmmmmmmm. What to say.... Bha. Let suppose you have supersymmetry with slepton coannihilating with neutralion (that happens) and let’s give that a name. You will call it «lepton portal». Except the fact that you can had a fermionic lepton in the t-channel and all kind of combinations summarizes in their Eq. (1) and (2), just go to their results on Fig.7 to look at the parameter space still living. Some subtleties coming from p-wave suppression and constraints from AMS/PAMELA. For the rest, you can find an annotated version of the paper here.

The Electroweak Vacuum Angle

by  P. F. Perez and H. H. Patel

In the SM the topological SU(2) terms can be rotated away (unlike the SU(3) one) by a B- or L-  symmetric rotation of fermions.  However, if B and L are violated by new operators beyond the SM then the topological SU(2) terms can be a new source of CP violation. The authors speculate that sphaleron processes  in the early universe could produce baryon asymmetry thanks to this topological term, although currently this is not calculable at the quantitative level.

The Ether and the Earth’s Atmosphere

by G.F. FitzGerald


Apter the Michelson and Morley’s experiment, the rush was not on the elimination of the aetherial principle but the idea developed by FitzGerald and Lorentz was on the possible contraction of the length of material body. This (very) short article published in Science is the first proposal of such revolutionar idea that will lead to Lorentz/Poincaré/Einstein transformation in 1904-1905.